Abstract: 【Objective】 The aim is to study the effects of different cultivation substrates and planting densities on the yield of onion bulblets. 【Methods】 With Baixue as the test material, the flat bottom seedling tray was used to sow, five kinds of cultivation substrates were designed, and four kinds of sowing densities were studied, A total of 15 treatments. This study lays the theoretical and technical foundation for realizing the mechanized colonization of onion bulblet as planting material. 【Results】 The results showed that the plant height of seedlings treated with sheep manure:garden soil = 1:3, density 2.5 cm × 2.5 cm was the highest, which was 25.95 cm, and the diameter of pseudostem was the thickest, which was 2.27 mm. The number of leaves treated with peat:perlite = 1:2, density 2.5 cm × 2.5 cm was the highest, which was 4.20. The peroxidase ( POD ) activity of peat:perlite = 1:2, density 2.5 cm × 2.5 cm treatment was significantly higher than those of other treatments, and the catalase ( CAT ) activity of sheep manure:garden soil = 1:3, density 1.5 cm × 1.5 cm treatment was significantly higher than those of other treatments. There was no significant difference in superoxide dismutase (SOD) among all density treatments of perlite:vermiculite = 1:3, but it was higher than other treatments. The content of malondialdehyde ( MDA ) in vermiculite:perlite = 1:2, density 2 cm × 2 cm treatment was the highest. Peat:perlite = 1:2, density 1.5 cm × 1.5 cm treatment per square centimeter of the largest number of bulbs, which was 35.55. 【Conclusion】 According to the comprehensive evaluation of membership function method, the treatment of peat:perlite = 1:2,density 2 cm × 2 cm ranks the first. The germination rate of this treatment group is 91.33 %, the plant height is 18.01 cm, the pseudostem diameter is 2.14 mm, the number of leaves is 3.89, and the number of bulbs ranks the third,good comprehensive characteristics.There is a significant positive correlation between the number of leaves and the pseudostem diameter ( r = 0.623, P < 0.05 ). There is a significant negative correlation between the number of bulbs and plant height (r=-0.518, P < 0.05 ). Under the interaction of density and substrate, the number of bulbs is significantly negatively correlated with plant height.